U.S. patent application number 10/990547 was filed with the patent office on 2006-05-18 for refrigerant charging by optimum performance.
This patent application is currently assigned to SNAP-ON INCORPORATED. Invention is credited to Craig Govekar, Kenneth Meldahl, Larry Moller, Dean Pfefferle, Anwar Suharno.
Application Number | 20060101835 10/990547 |
Document ID | / |
Family ID | 35717533 |
Filed Date | 2006-05-18 |
United States Patent
Application |
20060101835 |
Kind Code |
A1 |
Meldahl; Kenneth ; et
al. |
May 18, 2006 |
Refrigerant charging by optimum performance
Abstract
A charging system for charging a refrigeration system of a
vehicle includes a controller, a refrigerant source, at least one
line fluidly connecting the refrigerant source to the refrigeration
system; a control valve disposed to control flow of the refrigerant
from the refrigerant source to the refrigeration system, and an
efficiency sensor for measuring the efficiency of the refrigeration
system. The controller operates to cause the charging system to
input into the refrigeration system a predetermined amount of
refrigerant less than a recommended refrigerant charge amount;
measure a baseline efficiency of the refrigeration system, input a
supplemental amount of refrigerant into the refrigeration system,
measure an adjusted efficiency of the refrigeration system, and
compare the measured adjusted efficiency to the baseline efficiency
using the controller.
Inventors: |
Meldahl; Kenneth; (Fox Lake,
IL) ; Pfefferle; Dean; (Elgin, IL) ; Govekar;
Craig; (Gurnee, IL) ; Suharno; Anwar;
(Barrington, IL) ; Moller; Larry; (Harvard,
IL) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
SNAP-ON INCORPORATED
|
Family ID: |
35717533 |
Appl. No.: |
10/990547 |
Filed: |
November 18, 2004 |
Current U.S.
Class: |
62/149 ; 62/292;
62/77 |
Current CPC
Class: |
B60H 1/00585 20130101;
F25B 2345/001 20130101; F25B 2309/06 20130101; F25B 2345/007
20130101; F25B 9/008 20130101; F25B 45/00 20130101 |
Class at
Publication: |
062/149 ;
062/077; 062/292 |
International
Class: |
F25B 45/00 20060101
F25B045/00 |
Claims
1. A method of charging a refrigeration system, the method
comprising the steps of: inputting into the refrigeration system a
predetermined amount of refrigerant less than a recommended
refrigerant charge amount; establishing a baseline efficiency by
measuring an efficiency of the refrigeration system; inputting a
supplemental amount of refrigerant into the refrigeration system;
measuring an adjusted efficiency of the refrigeration system; and
comparing the measured adjusted efficiency to the baseline
efficiency.
2. The method according to claim 1, further comprising repeating
the steps of: establishing the baseline efficiency, inputting the
supplemental amount of refrigerant, measuring the adjusted
efficiency, and comparing the baseline efficiency to the adjusted
efficiency.
3. The method according to claim 2, wherein the steps of
establishing the baseline efficiency, inputting the supplemental
amount of refrigerant, measuring the adjusted efficiency, and
comparing the baseline efficiency to the adjusted efficiency are
repeated until a comparison of the measured adjusted efficiency to
the baseline efficiency yields a predetermined result.
4. A method of charging a refrigeration system according to claim
2, wherein the step of inputting the supplemental amount of
refrigerant includes inputting decreasing supplemental amounts of
refrigerant in at least two successive inputting steps.
5. A method of charging a refrigeration system according to claim
2, wherein a subsequent step of establishing the baseline
efficiency of the refrigeration system includes the prior step of
measuring the adjusted efficiency of the refrigeration system.
6. A method according to claim 1, wherein each of the measuring the
efficiency steps includes performing the measuring after a
stabilization period.
7. The method according to claim 1, wherein the efficiency of the
refrigeration system is based upon a measured temperature of air
output by the refrigeration system.
8. The method according to claim 7, wherein the step of inputting
the supplemental amount of refrigerant and subsequent step of
measuring the adjusted efficiency step are iteratively repeated
until a temperature measurement following the step of inputting is
greater than a temperature measurement prior to the step of
inputting.
9. The method according to claim 8, wherein an amount of
refrigerant added in the last inputting step is purged from the
refrigeration system.
10. The method according to claim 8, wherein the inputting step and
subsequent measuring the adjusted efficiency are iteratively
repeated until the measured temperature substantially
stabilizes.
11. The method according to claim 1, wherein the refrigerant is
carbon dioxide.
12. A system for charging a refrigeration system of a vehicle,
comprising: a controller; a refrigerant source including a
refrigerant; at least one line adapted for connection to a
connection point on the refrigeration system to fluidly connect the
refrigerant source to the refrigeration system; a control valve
disposed to control flow of the refrigerant from the refrigerant
source to the refrigeration system, the control valve being
controllable by the controller; and an efficiency sensor for
measuring the efficiency of the refrigeration system, wherein an
executable instruction set arranged, when executed by the
controller, to cause the system to perform the steps of: inputting
into the refrigeration system from the refrigerant source a
predetermined amount of refrigerant less than a recommended
refrigerant charge amount, establishing a baseline efficiency of
the refrigeration system using the data from the efficiency sensor,
inputting a supplemental amount of refrigerant from the refrigerant
source into the refrigeration system, measuring an adjusted
efficiency of the refrigeration system using data from the
efficiency sensor, and comparing the measured adjusted efficiency
to the baseline efficiency using the controller.
13. The system according to claim 12, wherein the efficiency sensor
is a thermocouple.
14. The system according to claim 12, wherein the refrigerant is
carbon dioxide.
15. The system according to claim 12, wherein the controller
directs the control valve to halt inputting of refrigerant into the
refrigeration system after a comparison of the measured adjusted
efficiency to the baseline efficiency yields a predetermined
result.
Description
TECHNICAL FIELD
[0001] The disclosure relates to a system and method of charging
air conditioning and refrigeration systems or units, such as those
used in automobiles, boats or ships, or other types of
vehicles.
BACKGROUND ART
[0002] Most refrigeration systems are not 100% free of leaks. Thus,
the amount (or mass) of refrigerant within the refrigeration system
decreases over time. Refrigeration systems, however, are designed
to operate with a specific amount of refrigerant. Therefore, loss
of refrigerant in a refrigeration system over time typically
reduces the efficiency of the refrigeration system. Also, if the
amount of refrigerant in the refrigeration system drops to a
certain level, the refrigeration system may cease to operate and/or
be damaged. For these reasons, a common maintenance operation for a
refrigeration system is to recharge the refrigerant within the
refrigeration system.
[0003] The recharging operation typically involves evacuating the
refrigeration system of any remaining refrigerant and, if present,
other materials within the refrigeration system. Once the
refrigeration system is evacuated, a predetermined amount of new
refrigerant is introduced into the refrigeration system. An
important component of conventional refrigeration charging systems
is the device that measures the amount of refrigerant introduced
into the refrigeration system. Since the refrigeration system is
designed to operate with a specific amount of refrigerant, too
little or too much refrigerant can reduce the effectiveness of the
refrigeration system.
[0004] One conventional device used to measure the amount of
refrigerant introduced into the refrigeration system is a load cell
(or scale). Essentially, the load cell measures the weight of a
tank containing the refrigerant before the refrigerant is
introduced into the refrigeration system and then afterwards. The
difference between the two readings is the amount of refrigerant
introduced into the refrigeration system. There are, however,
certain problems that are associated with the use of a load cell in
conventional charging systems. Load cells are sensitive to
vibration, which can throw off the measurements. Also, since the
load cell determines the weight of the entire tank used to supply
the refrigerant, when the weight of the tank is increased, the
sensitivity of the load cell is reduced.
[0005] Furthermore, recent advances in refrigeration technology
employ carbon dioxide as the refrigerant, which is stored at a
pressure as much as ten times higher than the pressure at which
conventional refrigerants are stored, and the resulting increase in
storage pressure necessitates thicker walls for the tank. These
thicker walls add additional weight to the tank, which further
decreases the sensitivity of the load cell.
[0006] As those skilled in the art appreciate, the manufacturers
specifications are generally accurate, but provide ranges of
acceptable charge to account for variances, even between identical
vehicle models. Some manufacturers, such as Mercedes-Benz, Volvo,
Saab and Fiat publish single or exact numbers for the required
charge (e.g., 800 grams). Other manufacturers, such as BMW, Ford,
VW and Peugeot, provide a target number with a tolerance range
(e.g., 750 grams +/-50 grams). Yet other manufacturers, such as
many Japanese manufacturers, specify an overall range (e.g.,
500-600 grams), and this variation can lead to confusion. There is,
therefore, a need for a refrigerant charging system and method that
is more accurate and vibration-resistant, and by which technicians
may independently assess an optimal refrigerant charge for the
refrigeration system.
SUMMARY OF THE DISCLOSURE
[0007] The present disclosure provides an example of a system and
method of charging air conditioning and refrigeration systems or
units.
[0008] In one aspect, a charging system is provided for charging a
refrigeration system of a vehicle. The charging system includes a
controller, a refrigerant source for carbon dioxide as the
refrigerant, at least one line fluidly connecting the refrigerant
source to the refrigeration system; a control valve disposed to
control flow of the refrigerant from the refrigerant source to the
refrigeration system, and an efficiency sensor for measuring the
efficiency of the refrigeration system.
[0009] In another aspect, the controller operates to cause the
charging system to input into the refrigeration system a
predetermined amount of refrigerant less than a recommended
refrigerant charge amount; measure an efficiency of the
refrigeration system using the data from the efficiency sensor to
establish a baseline efficiency; input a supplemental amount of
refrigerant from the refrigerant source into the refrigeration
system, measure an adjusted efficiency of the refrigeration system
using data from the efficiency sensor, and compare the measured
adjusted efficiency to the baseline efficiency using the
controller.
[0010] Other aspects and advantages of the present disclosure will
become apparent to those skilled in this art from the following
description of preferred aspects taken in conjunction with the
accompanying drawings. As will be realized, the disclosed concepts
are capable of other and different embodiments, and its details are
capable of modifications in various obvious respects, all without
departing from the spirit thereof. Accordingly, the drawings,
disclosed aspects, and description are to be regarded as
illustrative in nature, and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The foregoing and other features, aspects and advantages of
the present concepts are described in the following detailed
description which examples are supplemented by the accompanying
drawings, in which:
[0012] FIG. 1 shows an example of a charging system, according to
the disclosure; and
[0013] FIG. 2 is a flow chart of a method of charging a
refrigeration system, according to the disclosure.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] In accord with the disclosed concepts, there is provided, as
shown in FIG. 1, a charging system 10 for charging a refrigeration
system of a vehicle 32, such as an automobile. The charging system
10 includes a refrigerant source 12, a scale 18, a controller 28,
and a control valve 14. The controller (or computer) 28 may include
a processor, a memory device, and a display device. The refrigerant
source 12 includes a refrigerant, such as carbon dioxide, and the
scale 18 measures a weight of the refrigerant source 12. The weight
measured by the scale 18 is output to controller 28. A heat band 22
is optionally disposed about the refrigerant source 12. A line 16,
or optionally more than one line, depending upon the configuration
of the charging system 10, may be provided with conventional
couplers 20 for connection, at one end, to a connection point on a
refrigeration system of the vehicle 32, and at another end, to the
refrigerant source 12.
[0015] The control valve 14 may be disposed anywhere in the flow
path of the refrigerant from the refrigerant source 12 to the
refrigeration system of the vehicle 32 to control flow of the
refrigerant from the refrigerant source 12 to the refrigeration
system of the vehicle 32. As shown in FIG. 1, actuation of the
control valve 14 may be controlled by signals output from the
controller 28. Alternatively, the control valve 14 may be manually
actuated.
[0016] The controller 28 may be connected to at least one
efficiency sensor 19 that measures the efficiency of the
refrigeration system. The efficiency sensor 19 may be included as
part of the charging system 10. Alternatively, the efficiency
sensor 19 may already be present within the refrigeration system
and/or the vehicle 32. In one aspect of the charging system 10, the
efficiency sensor 19 is adapted for placement adjacent an outlet of
the vehicle refrigeration system, or at another position, which may
be internal to the either the engine compartment or passenger
compartment of the vehicle. The output of the efficiency sensor 19
may then be fed into the controller 28.
[0017] A method of operating the charging system is illustrated in
FIG. 2. For example, the controller 28 includes an executable
instruction set arranged, when executed by the processor, to cause
the processor to perform the steps of: (1) controlling the control
valve 14 to input into the refrigeration system a predetermined
amount of refrigerant less than the recommended refrigerant charge
amount; (2) measuring a baseline efficiency of the refrigeration
system with the efficiency sensor 19 after the refrigeration system
has attained a substantially steady state condition; (3)
controlling the control valve 14 to input a supplemental amount of
refrigerant into the refrigeration system; (4) measuring an
adjusted efficiency of the refrigeration system with the efficiency
sensor 19 following the inputting into the refrigeration system of
the supplemental amount of refrigerant and after the refrigeration
system has attained a substantially steady state condition; and (5)
comparing the measured adjusted efficiency of the refrigeration
system to the baseline efficiency of the refrigeration system.
Additional steps may be included before or after any of the
aforementioned steps.
[0018] Additional aspects of the instruction set may comprise, for
example, executable instructions which, when executed by the
controller 28, cause the controller 28 to perform the further steps
of (6) repeating the steps of measuring the baseline efficiency,
inputting the supplemental amount of refrigerant, measuring the
adjusted efficiency, and comparing the baseline efficiency to the
adjusted efficiency; and (7) measuring the baseline efficiency,
inputting the supplemental amount of refrigerant, measuring the
adjusted efficiency, and comparing the baseline efficiency to the
adjusted efficiency are repeated until a comparison of the measured
adjusted efficiency to the baseline efficiency yields a
predetermined result.
[0019] In the current system and method, the charging would be
initiated by connecting the charging system 10 to the refrigeration
system of the vehicle 32 in accord with the manufacturer's
recommendations and determining the refrigerant system
manufacturer's recommended charge amount, for example, by a
technician physically looking up the value in an electronic or
hardcopy database, by a microprocessor (e.g., a shop computer, a
handheld processing device, or a microprocessor connected to the
charging equipment) accessing (e.g., downloading or uploading) the
information from a local or remote memory following input of
information uniquely identifying the refrigeration unit or class of
refrigeration unit, or even by relying on the expertise of the
technician in charge of the charging procedure.
[0020] The recommended charge amount would be input into the
microprocessor or controller 28 of the charging system 10. When the
charging is started, the controller 28 opens the control valve 14
until a predetermined amount less than the recommended charge
amount is charged into the vehicle 32. Any manner of determining
the predetermined amount is acceptable for use in the present
system and method, for example, the predetermined amount may be
determined by a scale 18, such as typically used for such purpose.
Advantageously, since the accuracy of the scale is not required to
be as high as that for conventional refrigerant charging methods
for reasons disclosed below, there is no need for a high-resolution
scale to measure the amount of refrigerant that is charged into the
refrigeration system.
[0021] In one aspect of the present concepts, this predetermined
amount may range from about 70% to about 95% of the recommended
charge amount. It is preferred to set the predetermined amount to a
value between approximately about 80% to about 85% of the
recommended charge amount. The predetermined amount percentages may
be taken with respect to a manufacturer's only specified value
(e.g., 800 grams), base value without tolerances (e.g., 750 grams
for recommended charge amount of 750 grams+/-50 grams), or midpoint
of a specified range. The predetermined amount may also
advantageously be set with respect to other values including, but
not limited to, a level below a manufacturer's only specified value
(e.g., a value less than 800 grams, if 800 grams is specified as
the recommended charge amount), base value with the lower tolerance
(e.g., 700 grams for recommended charge amount of 750 grams+/-50
grams), or low value in a specified range.
[0022] Broadly, in accord with the present concepts, the weight of
refrigerant initially input into the refrigerant system is
generally less than the recommended charge for the refrigerant
system by some non-trivial amount (e.g., by an amount more than the
accuracy of the refrigerant load scale). The predetermined amount
of initial refrigerant charge is intended only to get the initial
weight of refrigerant in the refrigeration system "in the ballpark"
to a point at which the efficiency of the refrigeration system may
be reliably monitored. It should be noted, however, that in certain
instances, the weight of refrigerant initially input into the
refrigeration system may be more than the recommended charge from
the refrigeration system.
[0023] Concurrently with or immediately preceding the completion of
initial charging of refrigerant in the refrigerant system to the
predetermined amount, the control valve 14 is closed. The term
control valve 14 is intended to broadly include any means by which
a device may be used to control, divert or stop the flow of
refrigerant into the refrigeration system. The control valve 14 may
be actuated by a motor, solenoid, or other conventional actuating
device, or may be manually actuated, such as by rotation of a
handle attached to the valve stem. The weight of refrigerant input
into the refrigerant system may also be controlled by means other
than a control valve 14, or in combination with a control valve 14,
including, but not limited to, a variable speed pump or positive
displacement pump.
[0024] Following the initial charging of the refrigeration system,
the refrigeration system is operated. In the case of a vehicle 32,
the vehicle 32 is started and the refrigeration system of the
vehicle 32 is operated. It is preferred, but not necessary, to
operate the refrigeration system at the coldest setting for the
subsequent steps (e.g., for a vehicle 32, the refrigeration system
is set to the coldest setting). The refrigeration system may be
operated at a setting other than the coldest setting in accord with
the concepts disclosed herein.
[0025] In accord with the present concepts, the efficiency of the
refrigeration system is measured, for example, by placing an
efficiency sensor 19, such as a temperature probe at an outlet or
output vent of the refrigeration system to measure a temperature of
the chilled fluid (e.g., air) being output by the refrigeration
system. The temperature probe 19 may be placed in an interior of
the outlet or output vent refrigeration system, or may
alternatively be placed adjacent thereto or in the vicinity
thereof, but generally within a few inches of such outlet or output
vent. The placement of the temperature probe may be achieved, for
example, by a clamp, by a configurable stand adapted to move (e.g.,
translate and/or rotate) along or about one or more axes, or simply
by selecting a temperature probe that is physically configured to
permit insertion into the outlet or output vent. As another
example, the efficiency sensor 19 may already built in to the
refrigeration system of the vehicle 32 and the controller 28
connects to an output port of the efficiency sensor 19. Other types
of sensors 19 capable of measuring efficiency of a refrigeration
system are also acceptable for use with the charging system and
method.
[0026] The temperature probe 19 may output its measured data to the
charging equipment controller 28, such as by a data line or by a
carrier signal or pulsed signal, to enable automatic control of the
control valve 14. Alternatively, temperature data from the
temperature probe 19 may be output to a local display or indicator
to enable a technician to locally monitor the temperature and
control operation of the control valve 14.
[0027] In accord with the present concepts, the control valve 14 is
intermittently opened for short intervals to provide discrete and
measured bursts of refrigerant into the refrigeration system. The
actual weight or quantity of refrigerant emitted by each burst may
be tailored by an appropriate control over the degree of opening of
the control valve 14, control over the duration for which the
control valve 14 is held in an open or partially-opened position,
and even by use of separate by-pass lines containing flow
restrictors, orifices, small-diameter tubing, or other means or
combination of means by which the flow may be controlled to provide
a technician or controller 28 (e.g., microprocessor) sufficient
time to ensure that a discrete burst of an appropriate amount is
discharged into the refrigeration system. Likewise, other control
schemes may be implemented in accord with the present concepts to
achieve discrete bursts of refrigerant into the refrigeration
system.
[0028] The refrigerant source 12 may optionally be heated to
facilitate transfer of the refrigerant from the tank into the
refrigeration system. This heating may be accomplished by a heating
band 22 or heat trace, or the like, to place the refrigerant source
12 at a higher pressure than that of the refrigerant system to
which it is to be attached.
[0029] In one aspect, the discrete bursts of refrigerant may
comprise supplemental charges of about 0.5 to 5.0% of the
recommended charge amount and, still more preferably, between about
1%-2% of recommended charge amount. Alternatively, on an absolute
scale, the supplemental charge could comprise a fixed amount such
as, but not limited to, a charge of about 0.1 ounce or about 2-3
grams. The supplemental charge could comprise, for example, a fixed
amount such as about 0.25 ounce or about 7 grams. The supplemental
charge may also be varied during the course of charging. In one
example, if the initial predetermined amount of refrigerant input
into the refrigeration system is 80% of the recommended refrigerant
charge amount, the initial supplemental charge may be 5.0%, the
next charge 4%, the subsequent charge 3%, and so on until a present
value, such as the recommended refrigerant charge amount or full
charge is reached, at which time the supplemental charges may be
reduced to a lower value such as 1%, 0.50%, 0.25%, or other
selected value.
[0030] In certain aspects of the system and method, the controller
28 trends the efficiency (e.g., the temperature of the air output
by the operating refrigeration system) of the refrigeration system
to determine whether or not the efficiency is increasing, staying
substantially constant, or decreasing the addition of each
supplemental charge of refrigerant. It is expected that each the
initial supplemental charges of refrigerant will improve the
functioning of the refrigerant system and the efficiency of the
refrigeration system will increase, evidenced, for example, by a
decrease in temperature of the air output by the operating
refrigeration system.
[0031] Eventually, for example, within about 5% to about 10% of the
manufacturer's recommended charge amount, it is expected that the
supplemental charges of refrigerant will only modestly improve the
functioning of the refrigerant system, if at all. In other words, a
plateau will be reached and the efficiency of the refrigeration
system will stay substantially constant. If additional supplemental
charges of refrigerant are added once this plateau has been
reached, the refrigeration system will start to become overcharged
and the supplemental charges will negatively impact the efficiency
and functioning of the refrigerant system. Somewhere during this
plateau of efficiency, the addition of supplemental charges of
refrigerant to the refrigeration system may be halted by the
controller 28. After the addition of supplemental charges of
refrigerant into the refrigeration system has halted, an amount,
equal to the last supplemental charge of refrigerant added to the
refrigeration system, may be removed from the refrigeration
system.
[0032] Thus, in accord with the present method and system, the
refrigeration system will be provided with its optimal charge and
run at its highest efficiency, as verified during the charging
process. Since only a predetermined amount of the manufacturer's
recommended charge amount, by a rough percentage, is initially
input into the system, no risk of overcharging the system exists,
and a high-resolution scale is not required since the efficiency of
the refrigeration system, as opposed to weight, is used to
determine the optimal charge.
[0033] The embodiments described herein may be used with any
desired fixed or mobile refrigeration system, including but not
limited to a vehicle refrigeration system. Various aspects of the
present concepts have been discussed in the present disclosure for
illustrative purposes. It is to be understood that the concepts
disclosed herein is capable of use in various other combinations
and environments and is capable of changes or modifications within
the scope of the concepts expressed herein. Moreover, although
examples of the system and method were discussed, the present
concepts are not limited by the examples provided herein and
additional variants are embraced by the claims appended hereto.
* * * * *